Reaction of the Si₈O₂₀(SnMe₃)₈ Building Block with Silyl Chlorides:  A New Synthetic Methodology for Preparing Nanostructured Building Block Solids

A series of silicate based “building block” (bb) materials has been synthesized via the reaction of the cubic, spherosilicate Si₈O₂₀(SnMe₃)₈ with the chlorosilanes HSiCl₃, Me₂SiCl₂, and SiCl₄. The resulting materials are amorphous, porous, high surface area matrices composed of intact Si₈O₂₀ building blocks that are cross-linked together through a series of siloxane linkages formed from the reaction of trimethyltin groups on the spherosilicate precursor and the silyl chloride groups. These siloxane-based linkages provide chemically robust, covalent connections between building blocks. The distribution of chemically distinct linking groups may be influenced by manipulating initial stoichiometries, changing solvents, varying temperature, and using different linking silyl chlorides. General procedures for preparing silicate platforms having linking groups with specific connectivities to surrounding building blocks in the matrix are described. The synthetic strategy for preparing the building block matrices described here forms the basis for preparing a wide range of nanostructured solids in which the identity and distribution of linking groups can be controlled by design. Applications to heterogeneous catalysts are discussed.